Packaging space for an engine within a vehicle may be limited. In particular, a height, length, and/or width of an engine may be limited by a size of the vehicle. However, the large number of engine components, particularly for a diesel engine, may be difficult to fit within a frame of smaller vehicles. For example, the front end of an engine may include a plurality of drive mechanisms for driving engine components using rotational energy from a crankshaft of the engine. In particular, camshafts may be driven by camshaft pulleys that are rotationally coupled to a crankshaft directly through a drive belt. However, the inventors herein have recognized that coupling the camshaft pulleys directly to the crankshaft via a belt increases the size of the pulleys needed to maintain a desired gear ratio between the crankshaft and the camshafts. Thus, due to the increased size of the camshaft pulleys, such systems increase the overall height and/or width of the engine.
In one example, the issues described above may be addressed by a front end of an engine comprising, a first end of a crankshaft, an idler gear assembly including an idler gear and an idler pulley, the idler gear in meshing engagement with the first end of the crankshaft and the idler pulley coupled to and sharing a rotational axis with the idler gear, first and second camshaft pulleys positioned vertically above the idler gear assembly, and a cam drive belt contacting each of the first and second camshaft pulleys and the idler pulley. In this way, by coupling the camshaft pulleys to the idler gear, the size of the camshaft pulleys may be reduced, and thus the size of the engine system may correspondingly be reduced as well.
In another representation, a method for an engine may comprise transmitting rotational motion from a crankshaft to an idler gear, the idler gear meshing with a first end of the crankshaft via a plurality of interlocking teeth, rotating an idler pulley directly coupled with the idler gear via rotation of the idler gear, the idler gear and idler pulley sharing a rotational axis, and driving rotation of first and second camshaft pulleys through a cam drive belt driven by the idler pulley, the cam drive belt contacting an outer surface of the first and second camshaft pulleys and the idler pulley.
In yet another representation, a system for an engine may comprise a front end, comprising: a first end of a crankshaft, an idler gear assembly including an idler gear and idler pulley, the idler gear in meshing engagement with the first end of the crankshaft and the idler pulley coupled to and sharing a rotational axis with the idler gear, first and second camshaft pulleys coupled to first and second camshafts, respectively, and a cam drive belt contacting each of the first and second camshaft pulleys and the idler pulley and not the first end of the crankshaft, and a back end arranged opposite the front end, the back end including a flywheel coupled to a second end of the crankshaft. In some examples, the idler gear may include more teeth than the first end of the crankshaft. Additionally or alternatively, the idler gear may comprise a larger diameter than the first end of the crankshaft.
Thus, the idler gear may rotate at a slower rate than the crankshaft due to its greater number of teeth and larger diameter. As such, by coupling the camshaft pulleys to the slower rotating idler gear, the diameter of the camshaft pulleys may be reduced. By reducing the size of the camshaft pulleys, the overall size of the engine system may be reduced.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.